1. Field of the Invention
The present invention relates to a display device preferably employable for a telephone or a similar electric appliance and more particularly relates to a display device for clearly displaying information on a light permeable member with the aid of a light beam transmitted through the light permeable member from a light source such as light emitting diode, small lamp.
2. Description of the Related Art
To facilitate understanding of the present invention a typical conventional display device usable for a telephone will be described below with reference to FIGS. 1 and 2.
To assure that the telephone 1 is operated by depressing dial buttons 2 without any particular difficulty in a dark room or the like location, the dial buttons 2 are light permeable members made of translucent resin. The members lighted are from one side by a light beam transmitted from a light emitting diode 4 which is disposed in a casing 3 of the telephone 1 as illustrated in FIG. 2. Information 5 on the upper surface of the dial buttons 2 (see FIG. 1) is visually recognized by an user with the aid of part of a light beam (emitted from the light emitting diode 4 in the direction as identified by arrow marks in FIG. 2). This part of the light beam is dispersed upwardly in each of the dial buttons 2. The information 5 in FIG. 1 includes a letter, figure, symbol or a combination of such elements.
The conventional display device is constructed in the above-described manner such that the dial buttons 2 constituted by a light permeable member of translucent resin are lighted from the light beam transmitted from the light emitting diode 4 so that the information 5 on the upper surface of the dial buttons 2 is visually recognized by an user with the aid of a part of light beam (as identified by arrow marks A in FIG. 2). A drawback of the conventional display device that the intensity of light beam recognizable on the surface with information 5 is less than that of light beam (as identified by arrow marks A in FIG. 2) transmitted to the side wall of the dial buttons 2, resulting in reduced lighting efficiency. Thus, the information 5 often fail to be recognized clearly.
Further, in the conventional display device, this tendency of reduced lighting efficiency is remarkable particularly due to the fact that the telephone 1 is operated merely with power supply from a telephone cable, and therefore it is difficult to supply the display device with a sufficiently high intensity of light to allow an user to operate the telephone 1 in a dark room or similar location.